The applications of TiN films in IC technology (i.e., diffusion barrier, gate material, current conductor, and heater) are based on their high thermodynamic stability, low electrical resistivity, and high mechanical hardness. Sputtered stoichiometric TiN exhibits insignificant oxidation rate at temperatures below 4000 C [1], whereas a non- stoichiometric TiN starts to oxidize even at room temperature [2]. The oxidation behavior of thin TiN layers, realized by ALD technique, is hardly investigated. To further promote the use of ALD TiN in novel electron devices (e.g., 3D low-temperature electronics, TFTs, etc.) and for wafer post-processing, both the stability and evolution of the layer properties at different temperatures, during the device operation or processing in reactive plasmas, must be explored.